Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Part V
Dutch Auctions
Posted-offer
markets
Double Auctions
Multi-player Games: Auctions
and Markets
Multi-player Games: Auctions and Markets
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Second price sealed-bid auctions
checkers
while statement
variables into labels
Dutch Auctions
The later statement
Programs into buttons
Posted-offer markets
the contracts table
the contracts creation box
the contracts list box
Double Auctions
Dutch Auctions
Posted-offer
markets
Double Auctions
Second price sealed-bid auctions - I
Purpose: elicit the true value of a good (e.g. a mug)
for each of the subjects.
I each subject receives an initial endowment (20
euros)
I
I
each subject makes an offer for the mug (possibly
even above 20 euros). The offers are secret and
simultaneous.
the subject who makes the highest bid wins the
mug and has to pay a price equal to the second
highest bid.
in case of a tie, the winner is drawn at random
among the bidders who submitted the highest bid.
See second price auction.ztt
I
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
checkers
while statement
variables into
labels
Dutch Auctions
Posted-offer
markets
Double Auctions
Second price sealed-bid auctions - II
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
checkers
while statement
variables into
labels
Dutch Auctions
Posted-offer
markets
Double Auctions
checkers
Multi-player
Games: Auctions
and Markets
checkers are used to verify the validity of an input.
To create a checker, select the button you need to
“check”, then, from the menu:
Treatment→New checker
Second price
sealed-bid auctions
checkers
while statement
variables into
labels
Dutch Auctions
Posted-offer
markets
Double Auctions
while statement - I
To sort the winner at random in case of a tie, we use the
while statement:
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
checkers
while statement
variables into
labels
while(subjects.count(winner==1)>1){
subjects.do{
rand=if(winner==1, random(), 0);
}
subjects.do{
winner=if(rand==subjects.maximum(rand),1, 0);
}
}
Dutch Auctions
Posted-offer
markets
Double Auctions
while statement - II
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
checkers
The general use is:
while(condition){
program;
}
While the condition is TRUE, the program is executed.
Reminder: loops can be left with the key combination
Ctrl+Alt+F5.
while statement
variables into
labels
Dutch Auctions
Posted-offer
markets
Double Auctions
Variables into labels
In the Active screen of the Results stage, we tell
each participants whether he is the winner.
In the input label we write: <>You are
<winner|!text:1="";0="not ";> the winner.
This becomes:
I “You are the winner”, if the variable winner is
equal to 1
I “You are not the winner”, if the variable winner is
equal to 0
Do not forget the <> sign at the beginning.
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
checkers
while statement
variables into
labels
Dutch Auctions
Posted-offer
markets
Double Auctions
Dutch Auctions - I
A Dutch auction is an auction in which the auctioneer
begins with a very high asking price, which is
progressively lowered until some participant accepts the
auctioneer’s price, or until a predetermined time is over.
I
all subject are buyers
I
global variables:
I
I
I
I
initial asking price
duration of the auction (in seconds) → duration
step of decrease of the price → step
frequency of decrease of the price (in seconds) →
time interval
See dutch auction.ztt
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
The later
statement
Programs into
buttons
Posted-offer
markets
Double Auctions
Dutch Auctions - II
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
The later
statement
Programs into
buttons
Posted-offer
markets
Double Auctions
The later statement
In the Auction stage, we run the following program:
later(time_interval) repeat{
price=price-step;
duration=duration-time_interval;
}
The general form is:
later(a) repeat{
program;
}
Expression a is calculated. The resulting number of
seconds later, the program is executed.
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
The later
statement
Programs into
buttons
Posted-offer
markets
Double Auctions
The later statement
In the Auction stage, we run the following program:
later(time_interval) repeat{
price=price-step;
duration=duration-time_interval;
}
The general form is:
later(a) repeat{
program;
}
Expression a is calculated. The resulting number of
seconds later, the program is executed.
Note: to exit the loop, set a to a negative value.
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
The later
statement
Programs into
buttons
Posted-offer
markets
Double Auctions
Programs into buttons
When a subject tries to buy the good:
I check that the good has not been sold so far
I run a program to assign the good to the subject
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
The later
statement
Programs into
buttons
Posted-offer
markets
Double Auctions
Posted offer markets - I
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
I
subjects in the role of buyers and sellers
I
each seller makes an offer, without knowing the
offers made by other buyers.
I
buyers act sequentially, in random order
I
they can see all the sellers’ offers that are still open,
and choose which one to accept, if any.
I
accepted offers are not visible anymore to
subsequent buyers.
See posted offers markets.ztt
Dutch Auctions
Posted-offer
markets
the contracts
table
the contracts
creation box
the contracts
list box
Double Auctions
Posted offer markets - II
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
Posted-offer
markets
the contracts
table
the contracts
creation box
the contracts
list box
Double Auctions
The contracts table
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
Posted-offer
markets
the contracts
table
the contracts
creation box
the contracts
list box
Double Auctions
The contracts creation box
Records in the Contracts table are created via inputs
in the Contract Creation Box.
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
Posted-offer
markets
the contracts
table
the contracts
creation box
the contracts
list box
Double Auctions
Buyers enter the Acceptance stage one by
one
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
Posted-offer
markets
I
I
the variable Priority, if
set, defines the order
according to which
subjects enter the stage.
if Priority is not set,
subjects enter the stage
in random order.
the contracts
table
the contracts
creation box
the contracts
list box
Double Auctions
The contracts list box
Available offers are displayed in a Contract list box.
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
Posted-offer
markets
the contracts
table
the contracts
creation box
the contracts
list box
Double Auctions
The contracts list box
Available offers are displayed in a Contract list box.
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
Posted-offer
markets
the contracts
table
the contracts
creation box
the contracts
list box
Double Auctions
Double auctions - I
see the z-Tree Tutorial, pages: 57-66
I subjects in the role of buyers and sellers.
I
both sellers and buyers can make offers, at the
same time.
I
each seller and each buyer can make more than one
offer.
I
sellers and buyers can see all the open offers (made
by buyers and by sellers)
I
each seller can accept only one of the buyers’ offers.
each buyer can accept only one of the sellers’ offers.
See double auction.ztt
I
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
Posted-offer
markets
Double Auctions
Double auctions - II
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
Posted-offer
markets
Double Auctions
Double auctions - screenshot
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
Posted-offer
markets
Double Auctions
Double auctions - accepting an offer
1. set the ID of the
accepter
2. close all other offers
by the same proposer
and by the same
accepter
3. if all subjects have
signed a contract,
leave the stage
Note: the variable LeaveStage is preset in z-Tree.
Multi-player
Games: Auctions
and Markets
Second price
sealed-bid auctions
Dutch Auctions
Posted-offer
markets
Double Auctions